A thermistor is a type of resistor with resistance varying according to its temperature. Temperature sensors utilizing thermistors are widely used to monitor the temperature of various components in an engine. For example, the oil, coolant, and/or engine block temperature may be monitored. In many thermistor-based temperature sensors, one side of the thermistor is connected to a positive terminal that is further connected to a wire leading to a computer. The opposite side of the thermistor is often connected to the temperature sensor casing which in turn is connected to ground. As the surrounding temperature changes, the temperature of the thermistor changes and it's resistance value changes. Using a table of resistance values for reference, the computer may use the resistance value of the temperature sensor to determine the temperature of the thermistor.
In marine applications, such as boats, ships, and yachts, temperature sensors may be occasionally submerged in water or at least regularly come in contact with water. In such cases, there exists a need for a temperature sensor that does not utilize the temperature sensor casing for a return electrical path. Further, the computer may be physically mounted a long distance from the temperature sensor and may not share the same ground as the device being monitored. Additionally, the computer may be especially sensitive to electrical interference and thus must be electrically isolated from the device being monitored. In both cases, there exists a need for a temperature sensor that provides a dedicated return path to the computer for temperature monitoring.
Further, there exists a need for a temperature sensor that is both robust and durable, while being accurate, compact in size, and easy for a consumer to assemble or repair if required.